An oar is an implement used for water-borne

propulsion Propulsion is the generation of force by any combination of pushing or pulling to modify the translational motion of an object, which is typically a rigid body (or an articulated rigid body) but may also concern a fluid. The term is derived from ...

. Oars have a flat

blade A blade is the portion of a tool, weapon, or machine with an edge that is designed to puncture, chop, slice or scrape surfaces or materials. Blades are typically made from materials that are harder than those they are to be used on. Historic ...

at one end. Rowers grasp the oar at the other end. The difference between oars and

paddle A paddle is a handheld tool with an elongated handle and a flat, widened distal end (i.e. the ''blade''), used as a lever to apply force onto the bladed end. It most commonly describes a completely handheld tool used to propel a human-powered wa ...

s is that oars are used exclusively for

rowing Rowing is the act of propelling a human-powered watercraft using the sweeping motions of oars to displace water and generate reactional propulsion. Rowing is functionally similar to paddling, but rowing requires oars to be mechanically atta ...

. In rowing the oar is connected to the vessel by means of a

pivot Pivot may refer to: *Pivot, the point of rotation in a lever system *More generally, the center point of any rotational system *Pivot joint, a kind of joint between bones in the body *Pivot turn, a dance move Companies *Incitec Pivot, an Austra ...

point for the oar, either an

oarlock A rowlock , sometimes spur (due to the similarity in shape and size), oarlock (USA) or gate, is a brace that attaches an oar to a boat. When a boat is rowed, the rowlock acts as a fulcrum for the oar. On ordinary rowing craft, the rowlocks are ...

, or a thole. The oar is placed in the pivot point with a short portion inside the vessel, and a much larger portion outside. The rower pulls on the short end of the oar, while the long end is in the water. By contrast, paddles, are held in both hands by the paddler, and are not attached to the vessel. Rowers generally face the

stern The stern is the back or aft-most part of a ship or boat, technically defined as the area built up over the sternpost, extending upwards from the counter rail to the taffrail. The stern lies opposite the bow, the foremost part of a ship. Ori ...

of the vessel, reach towards the stern, and insert the blade of their oar in the water. As they lean back, towards the vessel's bow, the blade of their oars pivots in the oarlock, and the end in the water moves towards the stern, providing forward

thrust Thrust is a reaction force described quantitatively by Newton's third law. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction to be applied to that syst ...

. For thousands of years vessels were powered either by

sail A sail is a tensile structure—which is made from fabric or other membrane materials—that uses wind power to propel sailing craft, including sailing ships, sailboats, windsurfers, ice boats, and even sail-powered land vehicles. Sails may ...

s, or by the mechanical work of rowers, or by paddlers. Some ancient vessels were propelled by both oars and sail, depending on the speed and direction of the

wind Wind is the natural movement of air or other gases relative to a planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heating of land surfaces and lasting a few hou ...

History

Rowing oars have been used since the early Neolithic period. Wooden oars, with canoe-shaped pottery, dating from 5000–4500 BC have been discovered in a

Hemudu culture The Hemudu culture (5500 BC to 3300 BC) was a Neolithic culture that flourished just south of the Hangzhou Bay in Jiangnan in modern Yuyao, Zhejiang, China. The culture may be divided into early and late phases, before and after 4000 BC respecti ...

site at

Yuyao Yuyao () is a county-level city in the northeast of Zhejiang province, China. It is under the jurisdiction of the sub-provincial city of Ningbo. It is located west of central Ningbo, east of Hangzhou, bordering Hangzhou Bay in the north. Yuyao ...

Zhejiang Zhejiang ( or , ; , also romanized as Chekiang) is an eastern, coastal province of the People's Republic of China. Its capital and largest city is Hangzhou, and other notable cities include Ningbo and Wenzhou. Zhejiang is bordered by Jiang ...

, in modern China. In 1999, an oar measuring 63.4 cm (2 ft) in length, dating from 4000 BC, was unearthed in

Ishikawa Prefecture is a prefecture of Japan located in the Chūbu region of Honshu island. Ishikawa Prefecture has a population of 1,140,573 (31 October 2019) and has a geographic area of 4,186 km2 (1,616 sq mi). Ishikawa Prefecture borders Toyama Prefecture to ...

, Japan.

Construction

Oars have traditionally been made of wood. The form is a long shaft (or loom) with a flat blade on the end. Where the oar connects to the boat there is a "collar" (or button), often made of leather, which stops the oar slipping past the rowlock. Oars usually have a handle about 150mm long, which may be a material sleeve or alternatively an ovoid shape carved to fit the hands.

Physics

Oars are

levers A lever is a simple machine consisting of a beam or rigid rod pivoted at a fixed hinge, or ''fulcrum''. A lever is a rigid body capable of rotating on a point on itself. On the basis of the locations of fulcrum, load and effort, the lever is di ...

. Which class of lever depends on the

frame of reference In physics and astronomy, a frame of reference (or reference frame) is an abstract coordinate system whose origin, orientation, and scale are specified by a set of reference points― geometric points whose position is identified both mathema ...

. From the rower's perspective, the oar can be seen as a Class I lever. The oar is fixed in the oarlock, the rower pulls on the handle, and the blade moves in the opposite direction to propel the boat. The blade is further from the oarlock than the rower's hands. So, the heavy force of a short rowing motion becomes a smaller force over a greater distance. From an observer on the shore, the oar is instead a Class II lever. Here, the fulcrum is the ''blade'', planted in the water. The rower pulls on the handle and the boat moves along with them. The "Class II" perspective is important to competitive rowing. Effective rowers learn to lever the boat past the end of the blade, rather than pulling the blade through the water. The

World Rowing Federation World Rowing, also known as the World Rowing Federation (former abbreviation FISA; french: Fédération internationale des sociétés d'aviron), is the international governing body for rowing. Its current president is Jean-Christophe Rolland who ...

rulebook defines oars as Class II. Both the Class I and Class II perspectives can be used to calculate the forces on the rower, boat, and water, with equivalent results. The calculations are simpler for the Class I perspective. The

mechanical advantage Mechanical advantage is a measure of the force amplification achieved by using a tool, mechanical device or machine system. The device trades off input forces against movement to obtain a desired amplification in the output force. The model for t ...

of the oar depends on the length of the oar from the oarlock to the blade, compared to the length from the oarlock to the rower's hand(s). The further away from the oarlock the blade is, the more difficult it is to row and the more distance each stroke will move.

Balanced oar

This is a normal, usually wooden oar to which weight has been added at the inboard end so that the blade end is noticeably lighter and easier for a rower to operate without fatigue. The two methods of adding weight are to either have a much larger section in the oar immediately next to the handle for a distance of about or to drill an hole inside the handle for a distance of about and add about 12 oz of lead secured by epoxy resin glue. For a oar the balance point is about 12 inches outboard of the rowlock. Often surplus wood is removed from the blade's width and thickness and at the neck between the blade and the shaft to further reduce outboard weight. As the rower is expending less energy accelerating the (now-reduced) mass of the oar back-and-forth, and will experience less fatigue constantly exerting downward force on the handle (vs. an unbalanced version) -- this type of oar is more efficient and thus preferable for long-range rowing.

Oars used for transport

The oars used for transport come in a variety of sizes. The oars used in small

dinghies A dinghy is a type of small boat, often carried or towed by a larger vessel for use as a tender. Utility dinghies are usually rowboats or have an outboard motor. Some are rigged for sailing but they differ from sailing dinghies, which ...

or rafts can be less than 2 metres long. In classical times

warship A warship or combatant ship is a naval ship that is built and primarily intended for naval warfare. Usually they belong to the armed forces of a state. As well as being armed, warships are designed to withstand damage and are usually faster a ...

s were propelled by very long oars that might have several oarsmen per oar. These oars could be more than a

dozen A dozen (commonly abbreviated doz or dz) is a grouping of twelve. The dozen may be one of the earliest primitive integer groupings, perhaps because there are approximately a dozen cycles of the Moon, or months, in a cycle of the Sun, or year ...

metres long.

Oars used for competitive rowing

The oars used in

competitive rowing Rowing, sometimes called crew in the United States, is the sport of racing boats using oars. It differs from paddling sports in that rowing oars are attached to the boat using oarlocks, while paddles are not connected to the boat. Rowing is d ...

are long (250–300 cm) poles with one flat end about 50 cm long and 25 cm wide, called the blade. The part of the oar the oarsman holds while rowing is called the

handle A handle is a part of, or attachment to, an object that allows it to be grasped and manipulated by hand. The design of each type of handle involves substantial ergonomic issues, even where these are dealt with intuitively or by following tra ...

. While rowing, the oars are supported by metal frames attached to the side of the boat called riggers, while the oar fits into the oarlocks at the ends of each rigger. Classic oars were made of

wood Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin th ...

, but modern oars are made from synthetic material, the most common being

carbon fibre Carbon fiber-reinforced polymers (American English), carbon-fibre-reinforced polymers (Commonwealth English), carbon-fiber-reinforced plastics, carbon-fiber reinforced-thermoplastic (CFRP, CRP, CFRTP), also known as carbon fiber, carbon compo ...

Oars used as trophies

The sport of competitive rowing has developed a tradition of using an oar as a memento of significant race wins. A 'trophy oar' is not presented at the end of the race as a more familiar precious metal cup might be, but rather given by the club, school or university that the winning crew or rower represented. A trophy oar is a competition oar that has been painted in the club colours and has then had the details of the race signwritten on the face of the blade. The most common format would have the coat of arms or crest of the club or school positioned in the centre, with the crew names and the race details arranged around this. Many older universities (

Oxford Oxford () is a city in England. It is the county town and only city of Oxfordshire. In 2020, its population was estimated at 151,584. It is north-west of London, south-east of Birmingham and north-east of Bristol. The city is home to the ...

and

Cambridge Cambridge ( ) is a university city and the county town in Cambridgeshire, England. It is located on the River Cam approximately north of London. As of the 2021 United Kingdom census, the population of Cambridge was 145,700. Cambridge bec ...

would be prime examples, as well as Yale and Harvard) and their colleges have long histories of using the trophy oar and many examples are on display in club houses around the world.

In culture

The Norwegian municipalities of

Fedje Fedje is an island municipality in the Nordhordland region of Vestland county, Norway. The administrative centre of the municipality is the village of Fedje. The traditional economic activity of the inhabitants is fishing. The municipality is ...

and Herøy both have oars in their coat-of-arms. Oars have been used to describe various animals with characteristics that closely resemble the said rowing implement. The members of the Family Regalecidae, elongated deep-sea fishes, are called

oarfish Oarfish are huge, greatly elongated, pelagic lampriform fish belonging to the small family Regalecidae. Found in areas spanning from temperate ocean zones to tropical ones, yet rarely seen, the oarfish family contains three species in two gene ...

because their body shape is similar to that of an oar. The

hawksbill turtle The hawksbill sea turtle (''Eretmochelys imbricata'') is a critically endangered sea turtle belonging to the family Cheloniidae. It is the only extant species in the genus ''Eretmochelys''. The species has a global distribution, that is large ...

's genus of

Eretmochelys The hawksbill sea turtle (''Eretmochelys imbricata'') is a critically endangered sea turtle belonging to the family Cheloniidae. It is the only extant species in the genus ''Eretmochelys''. The species has a global distribution, that is large ...

is derived from the Greek root ''eretmo'', which roughly translates to ''oar''. The turtle was so-named because of the oar-like shape of its front flippers.

References

External links

Oar positions
1775 – 1783 British Navy {{Authority control Chinese inventions Marine propulsion Rowing equipment Water sports equipment